The present invention relates generally to single lens reflex cameras and more particularly to a mechanism for preventing or suppressing bounce or vibration of the mirror of such a camera when the mirror strikes stopper means located at one of two end positions of the mirror.
Generally, pivotable or tiltable mirrors of a single lens reflex camera are located between the camera objective lens and the camera shutter. In operation, the mirror of a single lens reflex camera is arranged to be moved between a first position where viewing of an object by a photographer may be effected through the mirror, with the mirror being located to block the optical path between the lens and film to be exposed. When an exposure operation is to occur, the mirror is pivoted out of the optical path and is then returned to its initial position to enable pre-exposure viewing of a subsequent photograph.
Thus, in a single lens reflex camera, the pivotable mirror located between the camera objective and the shutter is moved from a non-viewing position to a viewing position after each exposure has been completed. Generally, the motion of the mirror to the viewing position occurs by the action of its own weight augmented by the force of a return spring. Conventional mirror control mechanisms allow for the mirror to bounce from a stopper which usually defines the end position of the mirror at which the mirror is located to enable viewing through the lens of the camera. Since the time interval through which the repeated bouncing or vibration of the mirror occurs is extremely short when compared with the period of time involved in manually effecting one cycle of film winding operation and shutter cocking, the vibratory motion which the mirror undergoes does not tend to create serious problems with regard to exposure control.
Recently however automatic exposure control by utilization of motor drive mechanisms has become more and more popular. As a result, the high speed continuous succession of frame exposures occurring in this type of exposure operation has created a strong and growing demand for stabilization of mirror movement and suppression of the vibratory motion which the mirror tends to undergo when brought to the viewing position. This demand arises since without it improper exposures have tended to occur in a small proportion of the exposed frames as a result of a reduction in the accuracy of the exposure control. Vibratory or bouncing motion of the mirror tends to cause light coming from the objective lens to be shifted to a significant extent from the path of a photoelectric sensor which constitutes part of a TTL type of light metering system. In such systems, the signal from the sensor must be picked up in a very short time interval in order to derive an appropriate exposure value.
Thus, the present invention is intended to provide a device for stabilizing the movement of the tiltable mirror against vibratory motion when the mirror is returned to its viewing position.
A further aim of the invention is to provide a single lens reflex camera with a mirror bounce suppression device which will make it possible to successfully effect high speed continuous frame exposures while permitting an automatic exposure control apparatus to derive accurate and reliable exposure values.